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Navigated Transcranial Magnetic Stimulation (nTMS)

Policy Number: MP-556

Latest Review Date: July 2021

Category: Medicine                                                              

Policy Grade: C

POLICY:

Navigated transcranial magnetic stimulation is considered investigational for all purposes, including but not limited to, the preoperative evaluation of patients being considered for brain surgery.

DESCRIPTION OF PROCEDURE OR SERVICE:

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive imaging method for the evaluation of eloquent brain areas (e.g., controlling motor or language function). Navigated TMS is being evaluated as an alternative to other noninvasive cortical mapping techniques for presurgical identification of eloquent areas.

Management of Brain Tumors

Surgical management of brain tumors involves resecting the brain tumor and preserving essential brain function. “Mapping” of brain functions, such as body movement and language, is considered to be most accurately achieved with DCS, an intraoperative procedure that increases operating time and requires a wide surgical opening. Even if they are not completely accurate compared to DCS, preoperative techniques that map brain functions may aid in planning the extent of resection and the operative approach. Although DCS is still usually performed to confirm the brain locations associated with specific functions, preoperative mapping techniques may provide useful information that improves patient outcomes.

Noninvasive Mapping Techniques

The most commonly used tool for the noninvasive localization of brain functions is functional magnetic resonance imaging (fMRI). fMRI identifies regions of the brain where there are changes in localized cortical blood oxygenation, which correlates with the neuronal activity associated with a specific motor or speech task being performed as the image is obtained. The accuracy and precision of fMRI is dependent on the patient’s ability to perform the isolated motor task, such as moving the single assigned muscle without moving others. This may be difficult for patients in whom brain tumors have caused partial or complete paresis. The reliability of fMRI in mapping language areas has been questioned. Guissani et al (2010) reviewed several studies comparing fMRI and DCS of language areas and found large variability in sensitivity and specificity of fMRI. The discussion also points out a major conceptual point in how fMRI and DCS “map” language areas. fMRI findings reflect regional oxygenation changes, which show that a particular region of the brain is involved in the capacity of interest, whereas DCS locates specific areas in which the activity of interest is disrupted. Regions of the brain involved in a certain activity may not necessarily be required for that activity and could theoretically be safely resected.

Magnetoencephalography (MEG) also is used to map brain activity. In this procedure, electromagnetic recorders are attached to the scalp. In contrast to electroencephalography, MEG records magnetic fields generated by electric currents in the brain, rather than the electric currents themselves. Magnetic fields tend to be less distorted by the skull and scalp than electric currents, yielding improved spatial resolution. MEG is conducted in a magnetically shielded room to screen out environmental electric or magnetic noise that could interfere with the MEG recording.

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive imaging method for the evaluation of eloquent brain areas. Transcranial magnetic pulses are delivered to the patient as a navigation system calculates the strength, location, and direction of the stimulating magnetic field. The locations of these pulses are registered to a magnetic resonance imaging (MRI) image of the patient’s brain. Surface electromyography (EMG) electrodes are attached to various limb muscles of the patient. Moving the magnetic stimulation source to various parts of the brain causes EMG electrodes to respond; indicating the part of the cortex involved in particular muscle movements. For evaluation of language areas, magnetic stimulation areas that disrupt specific speech tasks are thought to identify parts of the brain involved in speech function. nTMS can be considered a noninvasive alternative to DCS, in which electrodes are directly applied to the surface of the cortex during craniotomy. nTMS is being evaluated as an alternative to other noninvasive cortical mapping techniques, such as fMRI and MEG, for presurgical identification of cortical areas involved in motor and language functions. Navigated TMS, used for cortical language area mapping, is also being investigated in combination with diffusion tensor imaging tractography for subcortical white matter tract mapping.

KEY POINTS:

This policy was updated using references identified in the MEDLINE database through April 15, 2021.

Summary of Evidence

For individuals who have brain lesion(s) undergoing preoperative evaluation for localization of eloquent areas of the brain who receive nTMS, the evidence includes systematic reviews, controlled observational studies and case series. Relevant outcomes are overall survival, test accuracy, morbid events, and functional outcomes. Several small studies have evaluated the distance between nTMS hotspots and direct cortical stimulation hotspots for the same muscle. Although the average distance in most studies is 10 mm or less, this does not take into account the error margin in this average distance or whether hotspots are missed. It is difficult to verify nTMS hotspots fully because only exposed cortical areas can be verified with direct cortical stimulation. Limited studies of nTMS evaluating language areas have shown high false-positive rates (low specificity) and sensitivity that may be insufficient for clinical use. Several controlled observational studies have compared outcomes in patients undergoing nTMS with those (generally pre-TMS historical controls) who did not undergo nTMS. Findings of the studies were mixed. A meta-analysis of observational studies found improved outcomes with preoperative nTMS mapping in patients with motor-eloquent brain tumors. However, in individual observational studies, outcomes were not consistently better in patients who underwent presurgical nTMS. For example, overall survival did not differ significantly between groups in two studies. The controlled observational studies had various methodologic limitations and, being nonrandomized, might not have adequately controlled for differences in patient groups, which could have biased outcomes. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Practice Guidelines and Position Statements

No guidelines or statements were identified.

U.S. Preventive Services Task Force Recommendations

Not applicable.

KEY WORDS:

Navigated transcranial magnetic stimulation, nTMS, Nexstim®, Nexstim NBS System 4, NexSpeech®

APPROVED BY GOVERNING BODIES:

In 2009, the eXimia Navigated Brain Stimulation System (Nexstim) was cleared for marketing by the U.S. Food and Drug Administration through the 510(k) process for noninvasive mapping of the primary motor cortex of the brain to its cortical gyrus for preprocedural planning.

Similarly, the Nexstim NBS System 4 and NBS System 4 with NexSpeech® received FDA 510(k) clearance in May 2012 for noninvasive mapping of the primary motor cortex and for localization of cortical areas that do not contain speech function, for the purposes of preprocedural planning.

BENEFIT APPLICATION:

Coverage is subject to member’s specific benefits. Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply.

FEP: Special benefit consideration may apply. Refer to member’s benefit plan. FEP does not consider investigational if FDA approved and will be reviewed for medical necessity.

CURRENT CODING:

CPT Codes:

As of 01/01/2018, there is no specific CPT code for this procedure. Use the following CPT code:

64999

Unlisted procedure, nervous system

Previous Coding:

0310T

Motor function mapping using noninvasive navigated transcranial magnetic stimulation (nTMS) for therapeutic treatment planning, upper and lower extremity (Deleted 12/31/2017)

REFERENCES:

  1. Conti A, Raffa G, Granata F, et al. Navigated Transcranial Magnetic Stimulation for "Somatotopic" Tractography of the Corticospinal Tract. Neurosurgery. Dec 2014; 10 Suppl 4:542-554.
  2. Forster MT, Hattingen E, Senft C et al. Navigated transcranial magnetic stimulation and functional magnetic resonance imaging: advanced adjuncts in preoperative planning for central region tumors. Neurosurgery 2011; 68(5):1317-24; discussion 24-5.
  3. Forster MT, Limbart M, Seifert V et al. Test-Retest-Reliability of Navigated Transcranial Magnetic Stimulation of the Motor Cortex. Neurosurgery 2013.
  4. Frey D, Schilt S, Strack V, et al. Navigated transcranial magnetic stimulation improves the treatment outcome in patients with brain tumors in motor eloquent locations. Neuro Oncol. Oct 2014; 16(10):1365-1372.
  5. Giussani C, Roux FE, Ojemann J et al. Is preoperative functional magnetic resonance imaging reliable for language areas mapping in brain tumor surgery? Review of language functional magnetic resonance imaging and direct cortical stimulation correlation studies. Neurosurgery 2010; 66(1):113-20.
  6. Hendrix P, Senger S, Simgen A, et al. Preoperative rTMS language mapping in speech- eloquent brain lesions resected under general anesthesia: a pair-matched cohort study. World Neurosurg. Apr 2017; 100:425-433.
  7. Jeltema HR, Ohlerth AK, de Wit A, et al. Comparing navigated transcranial magnetic stimulation mapping and gold standard direct cortical stimulation mapping in neurosurgery: a systematic review. Neurosurg Rev. Oct 03 2020.
  8. Jensen RL. Navigated transcranial magnetic stimulation: another tool for preoperative planning for patients with motor-eloquent brain tumors. Neuro Oncol. Oct 2014; 16(10):1299-1300.
  9. Kato N, Schilt S, Schneider H, et al. Functional brain mapping of patients with arteriovenous malformations using navigated transcranial magnetic stimulation: first experience in ten patients. Acta Neurochir (Wien). May 2014; 156(5):885-895.
  10. Krieg SM, Sabih J, Bulubasova L, et al. Preoperative motor mapping by navigated transcranial magnetic brain stimulation improves outcome for motor eloquent lesions. Neuro Oncol. Sep 2014; 16(9):1274-1282.
  11. Krieg SM, Shiban E, Buchmann N et al. Utility of presurgical navigated transcranial magnetic brain stimulation for the resection of tumors in eloquent motor areas. J Neurosurg 2012; 116(5):994-1001.
  12. Krieg SM, Sollmann N, Hauck T, et al. Repeated mapping of cortical language sites by preoperative navigated transcranial magnetic stimulation compared to repeated intraoperative DCS mapping in awake craniotomy. BMC Neurosci. 2014; 15:20.
  13. Krieg SM, Sollmann N, Obermueller T, et al. Changing the clinical course of glioma patients by preoperative motor mapping with navigated transcranial magnetic brain stimulation. BMC Cancer. 2015; 15:231.
  14. Mangraviti A, Casali C, Cordella R et al. Practical assessment of preoperative functional mapping techniques: navigated transcranial magnetic stimulation and functional magnetic resonance imaging. Neurol Sci 2013; 34(9):1551-1557.
  15. Nexstim. Healthcare providers: clinical evidence. www.nexstim.com/healthcare- providers/navigated-brain stimulation/clinical-evidence/.
  16. Opitz A, Zafar N, Bockermann V, et al. Validating computationally predicted TMS stimulation areas using direct electrical stimulation in patients with brain tumors near precentral regions. Neuroimage Clin. 2014; 4:500-507.
  17. Paiva WS, Fonoff ET, Marcolin MA, et al. Navigated transcranial magnetic stimulation in preoperative planning for the treatment of motor area cavernous angiomas. Neuropsychiatr Dis Treat. 2013; 9:1885-1888.
  18. Picht T. Current and potential utility of transcranial magnetic stimulation in the diagnostics before brain tumor surgery. CNS Oncol. Jul 2014; 3(4):299-310.
  19. Picht T, Krieg SM, Sollmann N et al. A comparison of language mapping by preoperative navigated transcranial magnetic stimulation and direct cortical stimulation during awake surgery. Neurosurgery 2013; 72(5):808-19.
  20. Picht T, Schmidt S, Brandt S, et al. Preoperative functional mapping for rolandic brain tumor surgery: comparison of navigated transcranial magnetic stimulation to direct cortical stimulation. Neurosurgery. Sep 2011;69(3):581-588; discussion 588.
  21. Picht T, Schulz J, Hanna M et al. Assessment of the influence of navigated transcranial magnetic stimulation on surgical planning for tumors in or near the motor cortex. Neurosurgery 2012; 70(5):1248-56; discussion 1256-1247.
  22. Raffa G, Scibilia A, Conti A, et al. The role of navigated transcranial magnetic stimulation for surgery of motor-eloquent brain tumors: a systematic review and meta-analysis. Clin Neurol Neurosurg. May 2019; 180: 7-17.
  23. Rizzo V, Terranova C, Conti A, et al. Preoperative functional mapping for rolandic brain tumor surgery. Neurosci Lett. Sep 16 2014; 583C:136-141.
  24. Schmidt S, Bathe-Peters R, Fleischmann R, et al. Nonphysiological factors in navigated TMS studies; Confounding covariates and valid intracortical estimates. Hum Brain Mapp. Aug 29 2014.
  25. Sollmann N, Hauck T, Hapfelmeier A, et al. Intra- and interobserver variability of language mapping by navigated transcranial magnetic brain stimulation. BMC Neurosci. 2013; 14:150.
  26. Sollmann N, Ille S, Boeckh-Behrens T, et al. Mapping of cortical language function by functional magnetic resonance imaging and repetitive navigated transcranial magnetic stimulation in 40 healthy subjects. Acta Neurochir (Wien). May 2 2016.
  27. Sollmann N, Ille S, Hauck T, et al. The impact of preoperative language mapping by repetitive navigated transcranial magnetic stimulation on the clinical course of brain tumor patients. BMC Cancer. 2015; 15:261.
  28. Sollmann N, Tanigawa N, Tussis L, et al. Cortical regions involved in semantic processing investigated by repetitive navigated transcranial magnetic stimulation and object naming. Neuropsychologia. Apr 2015; 70:185-195.
  29. Tarapore PE, Findlay AM, Honma SM et al. Language mapping with navigated repetitive TMS: Proof of technique and validation. Neuroimage 2013; 82:260-72.
  30. Tarapore PE, Picht T, Bulubas L, et al. Safety and tolerability of navigated TMS for preoperative mapping in neurosurgical patients. Clin Neurophysiol. Mar 2016; 127(3):1895-1900.
  31. Tarapore PE, Tate MC, Findlay AM et al. Preoperative multimodal motor mapping: a comparison of magnetoencephalography imaging, navigated transcranial magnetic stimulation, and direct cortical stimulation. J Neurosurg 2012; 117(2):354-62.
  32. Weiss C, Nettekoven C, Rehme AK et al. Mapping the hand, foot, and face representations in the primary motor cortex-- retest reliability of neuronavigated TMS versus functional MRI. Neuroimage 2013; 66:531-542.

POLICY HISTORY:

Medical Policy Panel, December 2013

Medical Policy Group, December 2013 (3): New policy; does not meet medical criteria for coverage and therefore considered investigational

Medical Policy Administration Committee, February 2014 Available for comment February 5 through March 21, 2014 Medical Policy Panel, December 2014

Medical Policy Group, February 2015 (6): Updated Key Points, Key Words, Approved by Governing Bodies and References; no change in policy statement.

Medical Policy Panel, June 2016

Medical Policy Group, July 2016 (6): Updated Description of Procedure, Key Points, Key Words, Summary of Evidence, Approved by Governing Bodies and References; no change in policy statement.

Medical Policy Panel June 2017

Medical Policy Group, June 2017 (6): Updates to Description, Key Points and References. No change to policy statement.

Medical Policy Group, December 2017: Annual Coding Update 2018. Created Previous Coding section and moved deleted code 0310T to this section. Added existing CPT code 64999 to current coding.

Medical Policy Panel, June 2018

Medical Policy Group, June 2018 (6): Updates to Key Points.

Medical Policy Group, December 2018 (6): Edit to policy statement verbiage. No change to policy intent.

Medical Policy Panel, June 2019

Medical Policy Group, July 2019 (3): 2019 Updates to Key Points and References. No changes to policy statement or intent.

Medical Policy Panel, July 2020

Medical Policy Group, July 2020 (3): 2020 Updates to Key Points. No changes to policy statement or intent.

Medical Policy Panel, June 2021

Medical Policy Group, July 2021 (3): 2021 Updates to Key Points and References. Policy statement    updated to remove “not medically necessary.” No other changes to policy statement or intent.


This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.